@reactivex/ix-esnext-esm
Version:
The Interactive Extensions for JavaScript
37 lines (35 loc) • 1.15 kB
JavaScript
import { IterableX } from '../iterablex.js';
/** @ignore */
export class DefaultIfEmptyIterable extends IterableX {
_source;
_defaultValue;
constructor(source, defaultValue) {
super();
this._source = source;
this._defaultValue = defaultValue;
}
*[Symbol.iterator]() {
let state = 1;
for (const item of this._source) {
state = 2;
yield item;
}
if (state === 1) {
yield this._defaultValue;
}
}
}
/**
* Returns the elements of the specified sequence or the default value in a singleton sequence
* if the sequence is empty.
*
* @template T The type of elements in the source sequence.
* @param {T} defaultValue The value to return if the sequence is empty.
* @returns {MonoTypeOperatorFunction<T>} An operator which returns the elements of the source sequence or the default value as a singleton.
*/
export function defaultIfEmpty(defaultValue) {
return function defaultIfEmptyOperatorFunction(source) {
return new DefaultIfEmptyIterable(source, defaultValue);
};
}
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